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/fs/coda/cache.c

https://bitbucket.org/cyanogenmod/android_kernel_asus_tf300t
C | 122 lines | 77 code | 19 blank | 26 comment | 9 complexity | cc7f823329e826c0fa3bdb06e228f1c8 MD5 | raw file
Possible License(s): LGPL-2.0, AGPL-1.0, GPL-2.0
  1/*
  2 * Cache operations for Coda.
  3 * For Linux 2.1: (C) 1997 Carnegie Mellon University
  4 * For Linux 2.3: (C) 2000 Carnegie Mellon University
  5 *
  6 * Carnegie Mellon encourages users of this code to contribute improvements
  7 * to the Coda project http://www.coda.cs.cmu.edu/ <coda@cs.cmu.edu>.
  8 */
  9
 10#include <linux/types.h>
 11#include <linux/kernel.h>
 12#include <linux/time.h>
 13#include <linux/fs.h>
 14#include <linux/stat.h>
 15#include <linux/errno.h>
 16#include <asm/uaccess.h>
 17#include <linux/string.h>
 18#include <linux/list.h>
 19#include <linux/sched.h>
 20#include <linux/spinlock.h>
 21
 22#include <linux/coda.h>
 23#include <linux/coda_psdev.h>
 24#include "coda_linux.h"
 25#include "coda_cache.h"
 26
 27static atomic_t permission_epoch = ATOMIC_INIT(0);
 28
 29/* replace or extend an acl cache hit */
 30void coda_cache_enter(struct inode *inode, int mask)
 31{
 32	struct coda_inode_info *cii = ITOC(inode);
 33
 34	spin_lock(&cii->c_lock);
 35	cii->c_cached_epoch = atomic_read(&permission_epoch);
 36	if (cii->c_uid != current_fsuid()) {
 37		cii->c_uid = current_fsuid();
 38                cii->c_cached_perm = mask;
 39        } else
 40                cii->c_cached_perm |= mask;
 41	spin_unlock(&cii->c_lock);
 42}
 43
 44/* remove cached acl from an inode */
 45void coda_cache_clear_inode(struct inode *inode)
 46{
 47	struct coda_inode_info *cii = ITOC(inode);
 48	spin_lock(&cii->c_lock);
 49	cii->c_cached_epoch = atomic_read(&permission_epoch) - 1;
 50	spin_unlock(&cii->c_lock);
 51}
 52
 53/* remove all acl caches */
 54void coda_cache_clear_all(struct super_block *sb)
 55{
 56	atomic_inc(&permission_epoch);
 57}
 58
 59
 60/* check if the mask has been matched against the acl already */
 61int coda_cache_check(struct inode *inode, int mask)
 62{
 63	struct coda_inode_info *cii = ITOC(inode);
 64	int hit;
 65	
 66	spin_lock(&cii->c_lock);
 67	hit = (mask & cii->c_cached_perm) == mask &&
 68	    cii->c_uid == current_fsuid() &&
 69	    cii->c_cached_epoch == atomic_read(&permission_epoch);
 70	spin_unlock(&cii->c_lock);
 71
 72	return hit;
 73}
 74
 75
 76/* Purging dentries and children */
 77/* The following routines drop dentries which are not
 78   in use and flag dentries which are in use to be 
 79   zapped later.
 80
 81   The flags are detected by:
 82   - coda_dentry_revalidate (for lookups) if the flag is C_PURGE
 83   - coda_dentry_delete: to remove dentry from the cache when d_count
 84     falls to zero
 85   - an inode method coda_revalidate (for attributes) if the 
 86     flag is C_VATTR
 87*/
 88
 89/* this won't do any harm: just flag all children */
 90static void coda_flag_children(struct dentry *parent, int flag)
 91{
 92	struct list_head *child;
 93	struct dentry *de;
 94
 95	spin_lock(&parent->d_lock);
 96	list_for_each(child, &parent->d_subdirs)
 97	{
 98		de = list_entry(child, struct dentry, d_u.d_child);
 99		/* don't know what to do with negative dentries */
100		if ( ! de->d_inode ) 
101			continue;
102		coda_flag_inode(de->d_inode, flag);
103	}
104	spin_unlock(&parent->d_lock);
105	return; 
106}
107
108void coda_flag_inode_children(struct inode *inode, int flag)
109{
110	struct dentry *alias_de;
111
112	if ( !inode || !S_ISDIR(inode->i_mode)) 
113		return; 
114
115	alias_de = d_find_alias(inode);
116	if (!alias_de)
117		return;
118	coda_flag_children(alias_de, flag);
119	shrink_dcache_parent(alias_de);
120	dput(alias_de);
121}
122